The present invention relates to an apparatus for detecting an angle and an angular velocity of a rotating member and a method of assembling the same, and more particularly to a steering sensor for detecting a an angle and steering angular velocity of a steering member.
Heretofore, an apparatus for detecting a steering angle and an angular velocity of a steering member generally included a disc mounted on a steering shaft, and a sensor secured to a steering column tube. Applicant also proposed an invention relating to how to the sensor is mounted, in a separate patent application (U.S. Ser. No. 547,353). The disc is designed to be rotated with the steering shaft, and has a number of small holes which are concentrically located thereon. The sensor has a luminescent element and a light receiving element, which are oppositely located on different axial sides of the disc and are positioned such that light emitted can pass through the holes of the disc and contact the light receiving element. When the steering shaft rotates by a driver's operation, the disc is forced to rotate with the steering shaft. In this condition, the light transmitted from the luminescent element to the light receiving element is interrupted by the rotation of the disc. The degree of the interruption is proportional to the number of the rotations of the disc. The degree of the interruption is converted to an electric pulse, thereafter and the steering angle and the steering angular velocity are calculated by the electric pulse.
It is quite difficult to assemble the disc and the sensor with high accuracy. Further, there is the possibility of bending the thin disc because the thin disc might be struck with one of the luminescent or light receiving elements during assembly thereof.